/**
 * Copyright (c) 2021 OceanBase
 * OceanBase CE is licensed under Mulan PubL v2.
 * You can use this software according to the terms and conditions of the Mulan PubL v2.
 * You may obtain a copy of Mulan PubL v2 at:
 *          http://license.coscl.org.cn/MulanPubL-2.0
 * THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
 * EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
 * MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
 * See the Mulan PubL v2 for more details.
 */

#ifndef OCEANBASE_SQL_ENGINE_EXPR_SUBSTR_
#define OCEANBASE_SQL_ENGINE_EXPR_SUBSTR_

#include "sql/engine/expr/ob_expr_operator.h"

namespace oceanbase {
namespace sql {

class ObExprSubstr : public ObStringExprOperator {
  public:
  explicit ObExprSubstr(common::ObIAllocator& alloc);
  virtual ~ObExprSubstr();
  virtual int calc_result2(common::ObObj& result, const common::ObObj& text, const common::ObObj& start_pos,
      common::ObExprCtx& expr_ctx) const;
  virtual int calc_result3(common::ObObj& result, const common::ObObj& text, const common::ObObj& start_pos,
      const common::ObObj& length, common::ObExprCtx& expr_ctx) const;
  virtual int calc_result_typeN(
      ObExprResType& type, ObExprResType* types_stack, int64_t param_num, common::ObExprTypeCtx& type_ctx) const;
  virtual int calc_resultN(
      common::ObObj& result, const common::ObObj* objs_array, int64_t param_num, common::ObExprCtx& expr_ctx) const;

  static int substr(common::ObString& output, const common::ObString& input, const int64_t pos, const int64_t len,
      common::ObCollationType cs_type);

  static int calc(common::ObObj& result, const common::ObString& text, const int64_t start_pos, const int64_t length,
      common::ObCollationType cs_type, const bool is_clob);

  virtual int cg_expr(ObExprCGCtx& op_cg_ctx, const ObRawExpr& raw_expr, ObExpr& rt_expr) const override;

  static int eval_substr(const ObExpr& expr, ObEvalCtx& ctx, ObDatum& expr_datum);

  private:
  int calc_result_length(
      ObExprResType* types_array, int64_t param_num, common::ObCollationType cs_type, int64_t& res_len) const;
  int calc_result2_for_mysql(common::ObObj& result, const common::ObObj& text, const common::ObObj& start_pos,
      common::ObExprCtx& expr_ctx) const;
  int calc_result2_for_oracle(common::ObObj& result, const common::ObObj& text, const common::ObObj& start_pos,
      common::ObExprCtx& expr_ctx) const;
  int calc_result3_for_mysql(common::ObObj& result, const common::ObObj& text, const common::ObObj& start_pos,
      const common::ObObj& length, common::ObExprCtx& expr_ctx) const;
  int calc_result3_for_oracle(common::ObObj& result, const common::ObObj& text, const common::ObObj& start_pos,
      const common::ObObj& length, common::ObExprCtx& expr_ctx) const;
  int cast_param_type_for_mysql(const common::ObObj& in, common::ObExprCtx& expr_ctx, common::ObObj& out) const;
  // disallow copy
  DISALLOW_COPY_AND_ASSIGN(ObExprSubstr);
};

}  // namespace sql
}  // namespace oceanbase
#endif /* OCEANBASE_SQL_ENGINE_EXPR_SUBSTR_ */
